As an electric power steering apparatus in the past, for example, there has been proposed an electric power steering apparatus in which a motor is housed in a part of a rack case or a steering gear box in which a rack shaft is slidably housed or mounted, a housing in which a control board for controlling to drive the motor is housed is formed in the rack case or the steering gear box, and, when the control board inserted from an opening of the housing is brought into contact with an attachment boss formed in a bottom portion opposed to the opening, a board connection terminal provided in the control board comes into contact with a motor side connection terminal protrudingly provided in the housing from the motor and is electrically connected thereto (see, for example, JP2005-329866A (hereinafter referred to as Patent Document 1), JP2005-329867A (hereinafter referred to as Patent Document 2), JP2005-329868A (hereinafter referred to as Patent Document 3), and JP2005-329869A (hereinafter referred to as Patent Document 4)). Patent Document 1 discloses the structure in which a female terminal is formed by a conductive spring piece or a male terminal is formed by a relatively long conductive plate piece in the board side connection terminal, a male terminal is formed by a relatively long conductive plate piece or a female terminal is formed by a conductive spring piece in the motor side connection terminal, and, when the control board is brought into contact with the attachment boss, the male terminal of the motor side connection terminal or the board side connection terminal is inserted into the female terminal of the board side connection terminal or the motor side connection terminal, the conductive spring piece of the female terminal is brought into press contact with the conducive plate piece of the male terminal by a spring force thereof, and contact of the female terminal and the male terminal is maintained.
In recent years, there is an increasing demand for improvement of mileage of vehicles and integrated control for the vehicles. Electric power steering apparatuses start to be adopted not only in small cars but also in large cars that require a large steering assisting thrust. In order to increase output of an electric motor that generates a steering assisting force, it is necessary to increase a motor current. However, according to the increase in the motor current, a wiring loss of a motor harness that connects a control unit, which controls to drive the electric motor, and the electric motor increases according to the increase in the motor current and efficiency falls.
Therefore, in the past, there is known an electric power steering apparatus in which a housing, to which a metal board is fixed in a closely attached state, is arranged on the opposite side of an electric motor, heat radiation fins are provided on an outer side of the housing and an inner side and an outer side of a cover attached to the electric motor, a power board, a large current board, and a control board are built in inner sides of the housing and the cover in a laminated structure, and a motor terminal projecting from the large current board to the outside of the cover is inserted into the electric motor and electrically connected to the electric motor (see, for example, JP2003-267233A (hereinafter referred to as Patent Document 5)).